Good point, Buzz. Starting with the easy stuff, copyright law does not prohibit resale, and antitrust law does not prohibit resale. Further, antitrust law could prohibit a seller from attempting to prevent resale.

Now, to get the antitrust laws involved, there generally has to be market power - perhaps not a monopoly, but something close. An artist would argue that he is not monopolzing or attempting to monopolize the art market, considering how many starving artists are out there. A buyer's attorney would argue that the artist is attemtping to monopolize the market for his own particular pieces so any buyer has to go to him to purchase, and cannot purchase in a secondary market.

So if the artist is relying on anything, it has to be contract law. An argument can be made that the contract is binding upon the buyer and the seller. Strong arguments could be made from both sides, I think. I'm not sure whether this particular issue has been litigated much (especially since artists like to have a secondary market to build reputation and demand). I remember the artist case Jim G. brought up. We had a similar problem in Detroit where the city threatened to remove a mural, and the artist claimed there was an agreement to keep it intact. The city next threatened to cover it up, which would not violate the agreement. Public pressure forced the city to reconsider the whole plan, though, and the mural remains intact to this day.

So let's say the artist has a valid contract. Now we jump to the next issue: if a buyer tries to resell it, what can the artist do? It is not a matter of criminal law (contracts are civil matters). It is highly questionable whether eBay would withdraw the item from sale unless it was a well-known artist with lots of political pull. Civil matters - contracts - are something eBay doesn't have the resourses to police on its own, and it would be cautious to interfere in an otherwise legal transaction. The artist would likely be left to sue the reseller, and even then he would have to show lost profits as his damages.

To top it off, the artist would probably have to go to the buyer's home state to file suit, making it an inconvenient proposition. If representing the artist, I would argue that it is a binding contract ("a contract is a contract"). If representing the reseller, I would argue that public policy inherently allows people to dispose of items they have purchased as they see fit - whether by sale, inheritance, trade, or trash, and unless the artist is prepared to match the offer he has no business interfering with the owner's inherent rights to the item. There is a chance the judge would think the artist was an idiot tying up valuable court time and foolishly trying to sue a local taxpayer and registered voter, and the artist would face a flurry of bad publicity. So I like my chances if I represent the Patron of the Arts rather than the mouth that bites his generous hand.

Accordingly, if I was advising a client about reselling this piece of art, I would give the above advice, tell the client it is not illegal to resell (he won't get arrested), and there is a slight risk of having the auction pulled and a slight risk of a lawsuit.